Fabrication of Enzyme-Free and Rapid Electrochemical Detection of Glucose Sensor Based on ZnO Rod and Ru Doped Carbon Nitride Modified Gold Transducer

Over 3 in 4 adults with diabetes live in low- and middle-income counties and health expenditure also increased 316% over the last 15 years. In this regard, we fabricate low cost, reusable and rapid detection of diabetes sensor based on zinc oxide rod inserted ruthenium-doped carbon nitride (ZnO-g-Ru-C₃N₄) modified sensor device. Developed sensor device physically and electrochemically characterized using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Sensing device as an effective enzyme-free glucose detection with high sensitivity (346 μA/mM/cm²) over the applied lower potential of +0.26 V (vs. Ag/AgCl), fast response (3 s) and broad linear range of (2-28) mM, coupled with a lower limit of detection (3.5 nM). The biosensing device gives better anti-interference ability with justifiable reproducibility, reusability (single electrode re-use 26 times in physiological buffer and 3 times in serum) and stability. Moreover, the real-time applicability of the sensor device was evaluated in human blood, serum and urine samples.

MnO₂/rGO Nanocomposites as a Supercapacitor Electrode Material

MnO₂ nanoparticles were incorporated in reduced graphene oxide (rGO) sheets employing an in-situ, one-step and eco-friendly method. The X-ray diffraction result shows that MnO₂ nanoparticles encapsulation increases the interlayer spacing of rGO. The UV-Vis, FTIR, X-ray photoelectron and Raman spectroscopic studies show that MnO₂ nanoparticles are well intercalated within reduced graphene oxide sheets. The electrochemical studies were executed in 0.5 M aqueous sulphuric acid. The maximum 'specific capacitance' value for MnO₂/reduced graphene oxide nanocomposite was 152.5 F/g at 0.05 V/s. The MnO₂/reduced graphene oxide (MnO₂/rGO) nanocomposite sample displayed an excellent charge retention capacity of 92% after 1000 cycles.

Fundamental Triangular Interaction of Electron Trajectory Deviation and P-N Junction to Promote Redox Reactions for the High-Energy-Density Electrode

Highly efficient redox reaction of active electrode materials is the guarantee for achieving high energy density for energy storage devices. Here, we design a triangle of the electrode material involving the P-N junction between NiO (p-type) and MoO₃ (n-type) and electron trajectory deviation between gold nanoparticles with NiO or MoO₃. This optimized fundamental triangle structure could facilitate the redox reaction of a metal oxide, and thus the fabricated ternary nanocomposites exhibit excellent electrochemical performance. At a lower current density (0.5 A g^-1), the mass specific capacitance of a single electrode can reach 943.3 F g^-1, while the NiO/MoO₃ tested under the same conditions only has a specific capacitance of 278.9 F g^-1. The assembled asymmetric device with activated carbon shows a higher capacitance retention rate of 98.7% after long-term cycling under different current densities, and a maximum energy density of 28.9 W h kg^-1 (power density of 400.1 W kg^-1). The crucial prerequisite of this strategy is the lower work function of gold nanoparticles compared with active materials, which significantly reduce the activation energy of NiO/MoO₃ and the formed P-N junction between p-type NiO with n-type MoO₃ in their contact interfaces. This novel design of a triangle structure could be expected to be applied in other materials to develop a kind of energy storage device with excellent electrochemical performance.

Review on Recent Progress in the Development of Tungsten Oxide Based Electrodes for Electrochemical Energy Storage

Current progress in the advancement of energy-storage devices is the most important factor that will allow the scientific community to develop resources to meet the global energy demands of the 21st century. Nanostructured materials can be used as effective electrodes for energy-storage devices because they offer various promising features, including high surface-to-volume ratios, exceptional charge-transport features, and good physicochemical properties. Until now, the successful research frontrunners have focused on the preparation of positive electrode materials for energy-storage applications; nevertheless, the electrochemical performance of negative electrodes is less frequently reported. This review mainly focuses on the current progress in the development of tungsten oxide-based electrodes for energy-storage applications, primarily supercapacitors (SCs) and batteries. Tungsten is found in various stoichiometric and nonstoichiometric oxides. Among the different tungsten oxide materials, tungsten trioxide (WO₃ ) has been intensively investigated as an electrode material for different applications because of its excellent charge-transport features, unique physicochemical properties, and good resistance to corrosion. Various WO₃ composites, such as WO₃ /carbon, WO₃ /polymers, WO₃ /metal oxides, and tungsten-based binary metal oxides, have been used for application in SCs and batteries. However, pristine WO₃ suffers from a relatively low specific surface area and low energy density. Therefore, it is crucial to thoroughly summarize recent progress in utilizing WO₃ -based materials from various perspectives to enhance their performance. Herein, the potential- and pH-dependent behavior of tungsten in aqueous media is discussed. Recent progress in the advancement of nanostructured WO₃ and tungsten oxide-based composites, along with related charge-storage mechanisms and their electrochemical performances in SCs and batteries, is systematically summarized. Finally, remarks are made on future research challenges and the prospect of using tungsten oxide-based materials to further upgrade energy-storage devices.

Selective Oxidation of Biomass-Derived Alcohols and Aromatic and Aliphatic Alcohols to Aldehydes with O2/Air Using a RuO2-Supported Mn3O4 Catalyst

Selective catalytic oxidation of carbohydrate-derived 5-hydroxymethylfurfural, furfuryl alcohol, and various aromatic and aliphatic compounds to the corresponding aldehyde is a challenging task. The development of a sustainable heterogeneous catalyst is crucial in achieving high selectivity for the desired aldehyde, especially using O2 or air. In this study, a RuO2-supported Mn3O4 catalyst is reported for the selective oxidation reaction. Treatment of MnO2 molecular sieves with RuCl3 in aqueous formaldehyde solution gives a new type of RuO2-supported Mn3O4 catalyst. Detailed catalyst characterization using powder X-ray diffraction, N2 adsorption, scanning and transmission electron microscopes, diffuse reflectance UV-visible spectrometer, and X-ray photoelectron spectroscopy proves that the RuO2 species are dispersed on the highly crystalline Mn3O4 surface. This catalytic conversion process involves molecular oxygen or air (flow, 10 mL/min) as an oxidant. No external oxidizing reagent, additive, or cocatalyst is required to carry out this transformation. This oxidation protocol affords 2,5-diformylfuran, 2-formylfuran, and other aromatic and aliphatic aldehydes in good to excellent yield (70-99%). Moreover, the catalyst is easily recycled and reused without any loss in the catalytic activity.

Zipping assembly of an Fe3O4/carbon nanosheet composite as a high-performance supercapacitor electrode material

A two-dimensional Fe₃O₄/carbon nanosheet was fabricated by zipping assembly and showed a good electrochemical performance as a supercapacitor electrode.

Noble metal-based materials in high-performance supercapacitors

This review comprehensively summarizes and evaluates the recent progress in the research of noble metals and their composite electrode materials for supercapacitors.

Fabrication and characterization of ultra light SiC whiskers decorated by RuO2 nanoparticles as hybrid supercapacitors

Ultra light SiC whiskers decorated by RuO₂ nanoparticles fabricated combining carbon thermal reduction and a hydrothermal route were investigated as novel hybrid supercapacitors with improved performance.

In situ growth of MnO2 nanosheets on activated carbon fibers: a low-cost electrode for high performance supercapacitors

MnO₂ nanosheets were successfully grown in situ on the surface of activated carbon fibers (ACFs) via a facile microwave-assisted hydrothermal method.

Synthesis of mesoporous NiCo2O4–rGO by a solvothermal method for charge storage applications

A facile and cost-effective solvothermal method is described for the synthesis of mesoporous NiCo₂O₄–rGO electrode material using PVP polymeric surfactant for supercapacitor application.